SIP 204 No Notification vs 488 Not Acceptable Here
SIP 204 (No Notification) is a 2xx Success response, while 488 (Not Acceptable Here) is a 4xx Client Failure response. 204 indicates that the request was successful but the server has decided not to send a NOTIFY for this SUBSCRIBE request. In contrast, 488 means that the request was understood but the session description (SDP) is not acceptable. The response may contain a list of acceptable media parameters.
Description
The request was successful but the server has decided not to send a NOTIFY for this SUBSCRIBE request.
When You See It
When subscribing to event packages that may not generate immediate notifications, such as dialog or presence packages.
How to Fix
No fix needed. The subscription was accepted but there is no state change to notify about yet.
Description
The request was understood but the session description (SDP) is not acceptable. The response may contain a list of acceptable media parameters.
When You See It
When codec negotiation fails — the callee cannot handle any of the codecs offered in the SDP. Common in interop scenarios.
How to Fix
Check the Warning header or SDP in the response for acceptable parameters. Add compatible codecs (e.g., G.711 as a fallback) to your offer.
Key Differences
204 is a 2xx Success response, while 488 is a 4xx Client Failure response.
SIP 204: The request was successful but the server has decided not to send a NOTIFY for this SUBSCRIBE request.
SIP 488: The request was understood but the session description (SDP) is not acceptable. The response may contain a list of acceptable media parameters.
You encounter 204 when when subscribing to event packages that may not generate immediate notifications, such as dialog or presence packages.
You encounter 488 when when codec negotiation fails — the callee cannot handle any of the codecs offered in the SDP. Common in interop scenarios.
When to Use Which
For 204 (No Notification): No fix needed. The subscription was accepted but there is no state change to notify about yet. For 488 (Not Acceptable Here): Check the Warning header or SDP in the response for acceptable parameters. Add compatible codecs (e.g., G.711 as a fallback) to your offer.